塔里木盆地塔中-巴楚地区侵入体温度场演化特征及其与油气储层的关系

Relation between the evolution of temperature field of intrusions and the development of carbonate reservoirs in Tazhong-Bachu area,the Tarim Basin

通过对塔中-巴楚地区奥陶系钻遇侵入体的岩石学、地球化学分析以及数值模拟等的详细研究，探讨了其热效应及对碳酸盐岩储层发育的影响。研究发现，塔中-巴楚地区碳酸盐岩中的层状侵入体为紫苏辉长岩和辉绿岩，紫苏辉长岩主要矿物有拉长石和紫苏辉石，副矿物有磷灰石等，辉绿岩主要矿物组合以单斜辉石和基性斜长石为主。地球化学分析表明，辉长岩的Si02含量介于44．58％-45．39％，K2O＋Na2O含量为3．91％-4．67％，Na20／K20含量比为2．16～4．23，属碱性系列；稀土元素配分模式属轻稀土元素富集型，LaN／YbN比值为5．010～5．980，铕异常参数8Eu值为0．910—1．002，Eu负异常很弱甚至没有Eu异常。塔中-巴楚地区层状侵入体热能传输理论模型与计算表明，层状侵入体温度的影响范围是有限的，侵入体对碳酸盐岩储层的热影响范围与其厚度密切相关，厚度越大影响范围越大。

Through microscopic identification, geochemical analysis and numerical simulation of the intrusions penetrated in the Tazhong-Bachu area, the paper discusses their thermal effect and influences upon the develop- ment of carbonate reservoirs. The study indicates that the layered intrusions in the carbonate reservoirs in the area are mainly of hypersthene gabbro and dolerite. The former has labradorite and hyperite as the host minerals and apatite as the accessory mineral,while the later has a host mineral assemblage consisting mainly of clinopy- roxene and basic plagioclase. Geochemical analysis shows that the gabbro from Well He-3 and He-4 belongs to alkaline series, with w （ SiO2 ） of 44.58 %- 45.39 %, w （ K2 0 ＋ Na20 ） of 3.91%- 4.67 %, and w （ Na20 ） / w（ K20） of 2.16%-4.23 %. Its partitioning pattern of REE is of LREE enrichment type,with LaN/YbN ranging from 5. 010 to 5. 980, and δEu from 0.910 to 1. 002, with very weak or even no negative Eu anomaly. The equa- tion of heat conduction was used to calculate temperature profiles adjacent to the thin layered intrusions during the cooling processes. The result points out that these intrusions have limited range of thermal effect, which is closely related to the thickness of intrusions： the thicker, the bigger.